In programming, not knowing the types or contents of variables exacerbates the difficulty in writing a program code. This may occur in dynamically-typed languages like JAVASCRIPT™, in which a variable's type is not clear from its definition, or in statically-typed languages like JAVA™, in which one may know that a variable is a string, but not know what the content of that string is supposed to be. These problems make it difficult for programmers to reason about and extend code written by others, or even code written by them and forgotten.
A known software debug program displays the flow of a program being debugged to a user. The program flow is illustrated in an example by highlighting the locations of sequential calls within the program being debugged, on a program structural representation which is presented on a display screen. In one example, a user is selectively able to stop the debug program at any observed step within the displayed flow sequence, to make programming changes or take another action as may be appropriate. In the example, the debug program user is also able to select an automatic sequencing through the flow of a program being developed and to designate a preferred display time duration for each step of the displayed sequencing.